WASHINGTON -- A deeply divided Senate went on record Wednesday in support of a landmark 1973 Supreme Court case on abortion, then worked methodically on legislation limiting the rights established in the ruling.

"We're finally here debating the most difficult, contentious social issue of our day," Sen. Sam Brownback R-Kan. said. "...What is the legal right of a child in utero?"

On that -- and that only, it seemed -- there was no debate.

Lawmakers clashed repeatedly, sometimes emotionally, over legislation to ban what critics call partial birth abortions, a procedure often performed in the 20th through 26th weeks of pregnancy.

"It's not medically necessary. It's not even medically recognized," Sen. Rick Santorum, R-Pa., said of the procedure to be banned.

"This bill doesn't protect the health of women. It puts our daughters in harm's way," countered Sen. Barbara Boxer, D-Calif., Santorum's principal antagonist across three days of debate.

Passage of the measure is expected today.

Abortion rights advocates scored one victory during the day, when the Senate voted 52-46 in support of the landmark 1973 Roe v. Wade ruling that gave women the right to end their pregnancies.

But that was a nonbinding verdict with no legal effect. And on the skirmishes that counted, abortion foes were in command.

On a vote of 60-38, the Senate first killed a proposal to ban a range of late-term abortions with exceptions for the health of the mother, exceptions that critics said rendered the prohibition all but meaningless.

Moments later, on a vote of 56-42, lawmakers rejected a call to have the bill rewritten in committee to address "constitutional issues raised by the Supreme Court" in a 2000 ruling.

The bill prohibits doctors from committing an "overt act" designed to kill a partially delivered fetus. Partial birth is described as a case in which the entire fetal head is outside the body of the mother, or, in the event of a breech delivery, if "any part of the fetal trunk past the navel is outside the body of the mother."

The legislation includes an exemption in cases in which the procedure is necessary to save the life of the mother.

Supporters of the bill say it would outlaw a procedure that is barbaric, never medically necessary and carried out in cases in which the fetus would survive if the pregnancy were allowed to continue.

Critics argue the legislation is unconstitutional because it is drafted so vaguely that it could apply to more than one type of procedure, and fails to provide an exemption to protect the health of a mother.

The day's events reflected hardened political lines on abortion, an issue that Sen. Richard Durbin, D-Ill., said was dividing America as deeply as slavery did in the 19th century. The Supreme Court ruled in 1973 that women had the right to abortions.

Durbin authored the proposal to ban a wider range of late-term abortions, but it drew opposition from abortion foes and abortion rights supporters as well.

It would have prohibited abortions after the point that the fetus could survive outside the mother, tempered by an exception in cases that threaten a mother's life or "risk grievous injury to her physical health."

"It doesn't ban abortion, which is what some people want. And it doesn't get the government out of the picture, which is what some other people want," he said. "Instead, it tries to draw a line, a good faith line of where we will allow abortions in late term pregnancies."

But Santorum criticized it. "It eliminates the ban on partial birth abortion," he said, and leaves it up to a doctor to decide when a fetus is viable. "If the doctor says this child is not viable there's no review" by the courts, he said.

Boxer proposed that the legislation be sent to committee to have it rewritten to take a 2000 Supreme Court ruling into account.

But Santorum said the bill's authors had written it to meet the court's standard, and disputed the need for a health exception. The legislation declares that a ban on the procedure would "advance the health interests of pregnant women seeking to terminate a pregnancy."

The 2000 court case turned on a Nebraska law that was designed to ban the same type of procedure that the Senate measure addresses. The Supreme Court ruled the state law unconstitutional, saying it placed an "undue burden" on a woman's right to an abortion.

Abortion opponents have been trying since 1995 to ban what they call partial birth abortions. Former President Clinton twice vetoed bills. A third attempt was sidetracked by the court's ruling in 2000. Yet another bid faltered in the last Congress when Democrats gained control of the Senate and refused the schedule a vote.